The Spares Company
Club Shop/Regalia
Parent Website
Contact Officials
Machine Registrar
Club Secretary
Membership Secretaries
MPH Editor and Forum Administrator.
Section Newsletters
Technical Databases
Photos
Home
What's new
Latest activity
Forums
New posts
What's new
New posts
Latest activity
Information
Bike Modifications
Machine Data Services
Manufacturers Manuals
Spare Parts Listings
Technical Diagrams
Whitakerpedia (Vincent Wiki)
The Club
MPH Material Archive
Flogger's Corner
Obituaries
VOC Sections
Local Sections
Local Section Newsletters
Miscellaneous
Club Assets
Club History
Club Rules
Machine Data Services
Meeting Documents
Miscellaneous
Essential Reading
Magazine/Newspaper Articles/Letters
Adverts and Sales Brochures
The Mighty Garage Videos
Bikes For Sale (Spares Company)
Log in
Register
What's new
New posts
Menu
Log in
Register
Install the app
Install
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Comet badly tuned or just underpowered?
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="Tom Gaynor" data-source="post: 22974" data-attributes="member: 4034"><p>The air lever drops an obstruction into the air flow, reducing it. It has no effect on the fuel. So if the motor goes faster when you close the air-lever, it needed a little less air. Ergo, it was too weak before. Note however that this has to be done carefully, slowly, because if you close it completely at full throttle, it'll choke itself to death.</p><p>Despair not: this is not rocket science, but it isn't simple, either. Amal's tuning procedure is still the best way to set up an Amal carb, but they make it sound more black and white than it is. </p><p>Many British bikes were overgeared. This gave a high theoretical top speed, useful for marketing, and perhaps great economy at moderate speeds, but acceleration suffered. International Nortons would do a calculated 125 mph. Yeah, sure, on the downhill run to Creg, with a following wind. On the flat they wouldn't pull anything like that. Trying to keep this simple, power delivery is not constant. If max power is at 6000 rpm, and at 6000 rpm in third, let us say your speed is 70 mph, and that power is exactly that required to overcome resistance, dropping 1500 revs into top drops the power, and the bike will slow down. Or won't go any faster. If however it picks up 5 or 10 mph on a downhill stretch, you'll often hold that: the downhill put you further up the power curve. When one revs it to the max before changing up, you're trying to get far enough up the power curve in the next higher gear to have some in hand to go faster. Easier maybe to think of a bicycle: you might go faster up a hill in a lower gear. With madame on the carrier it may need to be lower still. Taking a tooth off the gearbox sprocket lowers ALL the gears.</p><p>I used to mark the twistgrip so that I knew whether I was on 1/4, 1/2 or 3/4 throttle. Then I knew which part of the carb I had to adjust. Choking at 1/2 throttle means the needle is too high (rich) or low (weak). Easy to find out...</p><p>In fact, the biggest thing you've achieved, that many devoutly desire, is a bike that starts easily. Contrary to received wisdom the most important thing about a bike is not acceleration, road-holding, steering, or top speed, it's starting. Because if it won't start, nothing else matters. And 65 two-up isn't all THAT shabby.</p></blockquote><p></p>
[QUOTE="Tom Gaynor, post: 22974, member: 4034"] The air lever drops an obstruction into the air flow, reducing it. It has no effect on the fuel. So if the motor goes faster when you close the air-lever, it needed a little less air. Ergo, it was too weak before. Note however that this has to be done carefully, slowly, because if you close it completely at full throttle, it'll choke itself to death. Despair not: this is not rocket science, but it isn't simple, either. Amal's tuning procedure is still the best way to set up an Amal carb, but they make it sound more black and white than it is. Many British bikes were overgeared. This gave a high theoretical top speed, useful for marketing, and perhaps great economy at moderate speeds, but acceleration suffered. International Nortons would do a calculated 125 mph. Yeah, sure, on the downhill run to Creg, with a following wind. On the flat they wouldn't pull anything like that. Trying to keep this simple, power delivery is not constant. If max power is at 6000 rpm, and at 6000 rpm in third, let us say your speed is 70 mph, and that power is exactly that required to overcome resistance, dropping 1500 revs into top drops the power, and the bike will slow down. Or won't go any faster. If however it picks up 5 or 10 mph on a downhill stretch, you'll often hold that: the downhill put you further up the power curve. When one revs it to the max before changing up, you're trying to get far enough up the power curve in the next higher gear to have some in hand to go faster. Easier maybe to think of a bicycle: you might go faster up a hill in a lower gear. With madame on the carrier it may need to be lower still. Taking a tooth off the gearbox sprocket lowers ALL the gears. I used to mark the twistgrip so that I knew whether I was on 1/4, 1/2 or 3/4 throttle. Then I knew which part of the carb I had to adjust. Choking at 1/2 throttle means the needle is too high (rich) or low (weak). Easy to find out... In fact, the biggest thing you've achieved, that many devoutly desire, is a bike that starts easily. Contrary to received wisdom the most important thing about a bike is not acceleration, road-holding, steering, or top speed, it's starting. Because if it won't start, nothing else matters. And 65 two-up isn't all THAT shabby. [/QUOTE]
Insert quotes…
Verification
The Series 'A' Rapide was known as the '********' Nightmare?
Post reply
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Comet badly tuned or just underpowered?
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
Accept
Learn more…
Top